frequency response

Hello,
I have a quick question for you, what you think is the ideal frequency response for headphones being used with Kasina? I read in a forum that
even if the frequencies are higher than 20,000 hz the ear perceives sounds and will act on the shapes and lights.

There is some studies that suggest ultrasonic hearing is possible in humans... more so through bone conduction. http://en.wikipedia.org/wiki/Ultrasonic_hearing I have played with bone conduction a bit mainly for bass drivers and entrainment by vibration, but I do intend at some time to get some high end bone conduction headphones and try out the ultrasonic response.

However, all of the frequencies below say 16khz are rolled off in the factory audio so that the SpectraStrobe and AudioStrobe signals are clean. So any high quality 'pro' headphones would give the best sound. I like Sennheiser and Sony headphones for value versus performance. The Sennheiser HD 380 are really nice.